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Phytomenadione

AEMPS

Vitamin K1, haemostatic, antidote for coumarin anticoagulant overdose

ATC code: B02BA01

Brand names: Mephyton, AquaMEPHYTON, Konakion MM, Phytonadione USP

Updated · Methodology

Indications

A

Coagulopathy in cholestasis and malabsorption

First line

Vitamin K1 is first-line for vitamin K-deficient coagulopathy in cholestatic liver disease, malabsorption syndromes (cystic fibrosis, coeliac disease, short bowel syndrome), and long-term parenteral nutrition. Doses: 5–10 mg IM or subcutaneously daily for 3 days, then guided by INR. In children with cholestasis: 1–2 mg/kg. In patients with severe coagulopathy and bleeding: 10 mg slow IV with concurrent PCC or FFP transfusion.

Sources

  1. Clinics in Liver Disease: Chronic Complications of Cholestasis (2018)
  2. Clinical Nutrition: ESPEN-ESPGHAN-ECFS guidelines on nutrition care for infants, children, and adults with cystic fibrosis (2016)
  3. Journal of Pediatric Gastroenterology and Nutrition: Prevention of Vitamin K Deficiency Bleeding in Newborn Infants (2016)
  4. Clinical Nutrition: Vitamin K status in patients with short bowel syndrome (2012)
  5. Cochrane Database of Systematic Reviews: Vitamin K supplementation for cystic fibrosis (2020)

ICD-10: E56.1 · ICD-11: 5B59

A

Reversal of warfarin anticoagulant effect

First line

Phytomenadione is the antidote for warfarin and acenocoumarol overdose. 2020 and SETH 2020 recommend strategy by INR and clinical situation: INR 4.5–10 without bleeding – temporary anticoagulant hold; INR >10 without bleeding – add oral phytomenadione 2.5–5 mg; significant bleeding or emergency surgery – IV phytomenadione 5–10 mg plus prothrombin complex concentrate (PCC) 25–50 IU/kg. Fresh frozen plasma is second-choice if PCC unavailable. K1 effect develops over 6–12 hours, so emergency surgery requires concurrent PCC. After reversal, discussion with a haematologist before restarting anticoagulation.

Sources

  1. ACCP: Evidence-Based Management of Anticoagulant Therapy: ACCP 9th Edition (2012)
  2. Blood Advances: American Society of Hematology 2018 guidelines for management of venous thromboembolism: optimal management of anticoagulation therapy (2018)
  3. ACC: ACC Expert Consensus Decision Pathway on management of bleeding in patients on oral anticoagulants (2020)
  4. ГРЛС: Фитоменадион – Государственный реестр лекарственных средств (2026)
  5. Annals of Internal Medicine: Oral Vitamin K Versus Placebo to Correct Excessive Anticoagulation in Patients Receiving Warfarin (2009)
  6. SETH: Recomendaciones SETH para el manejo de la anticoagulación oral (2020)
  7. AEMPS: Ficha técnica de Konakion (fitomenadiona) (2023)

ICD-10: T45.5 · ICD-11: NE60

A

Vitamin K deficiency bleeding

First line

Phytomenadione (Konakion) is first-line prevention and treatment of haemorrhagic disease of the newborn (HDN). 2022 and AEPED recommend a single IM dose of 1 mg (0.5 mg if <1500 g) within the first hour of life in all term newborns. Without prophylaxis the risk of early HDN is about 0.25–1.7 per 1000 births and late HDN (age 2–12 weeks) 4–10 per 100 000, with high mortality from intracranial haemorrhage. Oral regimens (2 mg at birth + 2 mg at day 4–6 + 2 mg at week 4–6) are only acceptable on categorical refusal of injection with informed parental consent. In adults with deficiency from malabsorption, prolonged antibiotic therapy or hepatic failure, 10–20 mg orally or 5–10 mg IM.

Sources

  1. AAP: Vitamin K and the newborn infant – policy statement (reaffirmed) (2022)
  2. AEMPS: Ficha técnica de Konakion (fitomenadiona) (2023)

ICD-10: P53 · ICD-11: KA8F

A

Vitamin K deficiency bleeding (VKDB) prevention in newborns

First line

Global paediatric standard: vitamin K1 1 mg intramuscularly once within the first 6 hours of life for term newborns; 0.4 mg/kg for preterm under 1,500 g, 0.5–1 mg for preterm above 1,500 g. , NG194, and 2022 unanimously recommend the intramuscular route. Alternative oral regimens (3 doses of 2 mg on days 1, 4–7, and 28) are acceptable when parents refuse injection, but efficacy is lower: late VKDB rate is 1.2–6.4 per 100,000 live births with oral regimens versus 0.25 per 100,000 after IM. Without prophylaxis, late VKDB causes intracranial haemorrhage with up to 20 % mortality and severe disability. K1 (phytomenadione) is used for this purpose, not K3 (Vikasol) – K3 causes haemolytic anaemia in neonates.

Sources

  1. AAP: Controversies Concerning Vitamin K and the Newborn (2003)
  2. NICE: Postnatal care (NG194) (2021)
  3. WHO: WHO Recommendations on Maternal and Newborn Care for a Positive Postnatal Experience (2022)
  4. Cochrane: Prophylactic vitamin K for vitamin K deficiency bleeding in neonates (2000)
  5. Минздрав РФ: Нормальная беременность. Клинические рекомендации (2023)
  6. ГРЛС: Фитоменадион – Государственный реестр лекарственных средств (2026)

ICD-10: P53 · ICD-11: KA8F

Marketing claims without evidence base

The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.

F

Anti-aging and longevity

Not recommended

Vitamin K1 (phytomenadione) is a fat-soluble vitamin found in green leafy vegetables. Its clinical indications are prevention and treatment of hemorrhagic disease of the newborn, bleeding on vitamin K antagonists, and hypoprothrombinemia. In anti-aging supplement marketing, vitamin K1 is sold as an anti-aging agent (often with vitamin D3 and calcium). International guidelines do not mention vitamin K1 as an anti-aging agent. Vitamin K1 is dangerous in people on warfarin or other vitamin K antagonists – it sharply reduces their effect with thrombosis risk. If vitamin K1 is being taken for anti-aging, consider seeking a second opinion, especially if you take anticoagulants.

Sources

  1. Cochrane: Prophylactic vitamin K for vitamin K deficiency bleeding in neonates (2000)
F

Osteoporosis

Not recommended

Phytomenadione (vitamin K1) is marketed «for bone health and osteoporosis prevention», blurring with vitamin K2 marketing. K1 and K2 are biologically distinct: K1 comes from vegetables and goes mainly to the liver for clotting factor synthesis; K2 (menaquinones) is synthesised by gut microbiota and linked to osteocalcin activation in bone. Large K1 RCTs in osteoporosis (ECKO trial 2008, NEJM) showed no fracture reduction. and ESCEO recommend adequate calcium+vitamin D, physical activity and smoking cessation for fracture prevention; in confirmed osteoporosis, bisphosphonates, denosumab or anabolics. If K1 was recommended «for osteoporosis», consider seeking a second opinion. Important: vitamin K reduces the effect of warfarin and other vitamin K antagonists; patients on these anticoagulants, including those with a mechanical heart valve, must not take vitamin K supplements without medical agreement.

Sources

  1. AEMPS: Ficha técnica de Konakion (fitomenadiona) (2023)

ICD-10: M81 · ICD-11: FB83.1

How to read tiers A–F
  • AStrong evidence – first or second line in international guidelines
  • BRecommended in selected cases
  • CStudy data contradict each other
  • DBenefit not proven, no documented harm
  • FDocumented harm, or risk without benefit

Mechanism of action

Phytomenadione (vitamin K1) is the essential cofactor for γ-carboxylation of glutamate residues in clotting factors II, VII, IX, X and proteins C and S. Without vitamin K these factors are synthesised in an inactive form (PIVKA). In deficiency or coumarin blockade clotting factors are non-functional and coagulopathy develops. Phytomenadione restores synthesis of active factors over 6–12 hours orally or 1–2 hours intravenously. Half-life 1.5–3 hours; in coumarin coagulopathy the effect persists 6–24 hours.

Safety

Contraindications

  • Hypersensitivity to phytomenadione or product components
  • IV bolus administration without dilution is forbidden (risk of fatal anaphylactoid reactions, especially in children)

Serious adverse effects

  • Anaphylactoid reactions and death with rapid IV administration (give over 30+ minutes, dilute in 5% glucose)
  • Haemolytic anaemia in G6PD-deficient newborns at high doses
  • Kernicterus in preterm infants at excessive doses

Common adverse effects

  • Injection-site irritation
  • Transient facial flushing
  • Altered taste

Pregnancy: can you take Phytomenadione?

AEMPS summary of product characteristics (section 4.6): no controlled studies of phytomenadione (Konakion) have been done in pregnant animals or women. Based on wide clinical experience, neither vitamin K1 nor the excipients of the formulation have toxic effects on reproduction at recommended doses. Phytomenadione is given to pregnant women when the benefit to the mother outweighs the risk to the fetus. Because vitamin K1 does not cross the placenta easily, it is not recommended in late pregnancy for prophylaxis of haemorrhagic disease of the newborn.

Breastfeeding: can you take Phytomenadione?

Compatible (Hale L1). Phytomenadione transfers into milk in small amounts. Despite this, HDN prophylaxis in the newborn remains mandatory – milk content is insufficient for adequate infant K levels.

Calculate RID

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Practical notes

Timing and administration

Newborn: intramuscular injection of 1 mg into the antero-lateral thigh within the first 6 hours of life. Adults for warfarin reversal: oral or slow intravenous (over 30 minutes). Faster IV administration is associated with anaphylactoid reactions and cardiac arrest. Subcutaneous administration in adults is an acceptable alternative with slower onset.

Monitoring

After warfarin reversal, INR is checked at 6, 12, and 24 hours post-K1. After standard newborn prophylaxis, no specific monitoring is required. In cholestasis- or malabsorption-related coagulopathy, INR is monitored every 1–3 days until stable, then clinically.

Special situations

In warfarin patients requiring rapid re-anticoagulation (mechanical heart valve, recent VTE), high-dose K1 hinders warfarin re-saturation for 1–2 weeks. In such cases, the minimum effective K1 dose is used, with PCC or FFP for immediate INR correction. In G6PD deficiency, high-dose intravenous K1 may cause haemolysis.

Common myths

Vitamin K1 for newborns and vitamin K in supplements are different products with different evidence bases. Common misconceptions include the following.

Myth: «the vitamin K shot at birth is unnecessary, you can refuse or use drops». Fact: intramuscular K1 1 mg in the first hours of life is the unanimous recommendation of , , , and Russian normal-pregnancy guidelines. Without prophylaxis, the late VKDB risk with intracranial haemorrhage is 4–7 per 100,000 live births. Oral regimens are acceptable when injection is refused but are less effective.

Myth: «Vikasol can be given to an infant instead of K1». Fact: Vikasol is K3 (menadione sodium bisulfite), a synthetic molecule. In newborns, K3 causes haemolytic anaemia and kernicterus risk. , ESPGHAN, and explicitly state that only K1 (phytomenadione) is used for VKDB. International paediatric practice has not used K3 for decades. Russian package inserts still list Vikasol as a «vitamin K» drug – this is outdated practice.

Myth: «vitamin K at birth is linked to childhood leukaemia». Fact: this hypothesis came from a single Golding et al. 1992 paper. Subsequent large epidemiological studies (Roman 2002, Fear 2003, McKinney 2003) did not confirm the association. in its position statement explicitly rejects the hypothesis. Refusing K1 prophylaxis based on this myth raises real VKDB risk.

Myth: «K1 and K2 are interchangeable – they are just vitamins K». Fact: different molecules, different target tissues, different indications. K1 (phytomenadione) acts on hepatic clotting factors – the only form for VKDB and warfarin reversal. K2 (menaquinone) acts on tissue Gla proteins – marketed for bones and vessels with weak clinical basis. They do not substitute for each other across indications.

Myth: «extra K1 in adults improves clotting». Fact: in a healthy adult, vitamin K is not deficient and clotting factors synthesise normally. Supplemental K1 without a clinical indication has no effect. In patients on warfarin, supplemental K1 is dangerous – it disrupts anticoagulation.

Drug–drug interactions

1 pair found. Sorted from critical to minor.

MajorWarfarinVitamin K antagonist anticoagulants

Mechanism

Warfarin works precisely by antagonising vitamin K: it blocks the recycling that activates factors II, VII, IX and X. Giving vitamin K1 reverses the drug directly. NIH ODS describes this as a serious and potentially dangerous interaction and stresses that consistency is what matters: sudden changes in intake, in either direction, destabilise the INR.

Symptoms

Adding vitamin K drops the INR below range and thrombotic risk returns: leg pain and swelling, sudden breathlessness, neurological deficit. Stopping it abruptly does the reverse, with a high INR, bleeding gums, bruising and dark urine.

Management

Do not add vitamin K to warfarin therapy on your own. Anyone already taking it should not stop abruptly: the aim is steady intake, leafy greens included, with more frequent INR checks during the first weeks of any change. Vitamin K1 as an antidote in overdose is handled in hospital and has nothing to do with the daily supplement.

Sources

Pair details →Warfarin →

Label mentions4 mentions

Verbatim lines from the interaction sections, in the language of the label

From this drug’s label

  • Majoranticoagulantesclass named in the label
    «Konakion 10 mg/ml no debe ser administrado intramuscularmente a pacientes bajo tratamiento anticoagulante dado que esta vía tiene características depot , por lo que la liberación continua de vitamina…»

    AEMPS, section 4.3 · Open on CIMA

  • MajorWarfarin
    «La vitamina K 1 antagoniza el efecto de los anticoagulantes derivados de la cumarina (como acenocumarol y warfarina).La coadministración de anticonvulsivantes puede afectar la acción de la vitamina K…»

    AEMPS, section 4.5 · Open on CIMA

  • antiepilépticosclass named in the label
    «La vitamina K 1 antagoniza el efecto de los anticoagulantes derivados de la cumarina (como acenocumarol y warfarina).La coadministración de anticonvulsivantes puede afectar la acción de la vitamina K…»

    AEMPS, section 4.5 · Open on CIMA

From other drugs’ labels

  • ModerateWarfarin
    «Vitamina K (fitomenadiona, menadiona): puede inhibir el efecto anticoagulante, por antagonismo de sus acciones sobre la síntesis de los factores de coagulación.»

    AEMPS, section 4.5 · Open on CIMA

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Frequently asked

What is Phytomenadione used for?

Phytomenadione is evaluated for the following indications with varying evidence strength: Vitamin K deficiency bleeding (evidence tier A), Coagulopathy in cholestasis and malabsorption (evidence tier A), Reversal of warfarin anticoagulant effect (evidence tier A). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Phytomenadione?

Common side effects of Phytomenadione (≥ 1 in 100): Injection-site irritation, Transient facial flushing, Altered taste. See the Safety section for uncommon and serious reactions.

Is Phytomenadione safe during pregnancy?

AEMPS summary of product characteristics (section 4.6): no controlled studies of phytomenadione (Konakion) have been done in pregnant animals or women. Based on wide clinical experience, neither vitamin K1 nor the excipients of the formulation have toxic effects on reproduction at recommended doses. Phytomenadione is given to pregnant women when the benefit to the mother outweighs the risk to the fetus. Because vitamin K1 does not cross the placenta easily, it is not recommended in late pregnancy for prophylaxis of haemorrhagic disease of the newborn.

Is Phytomenadione compatible with breastfeeding?

Compatible (Hale L1). Phytomenadione transfers into milk in small amounts. Despite this, HDN prophylaxis in the newborn remains mandatory – milk content is insufficient for adequate infant K levels.

Who should not take Phytomenadione?

Phytomenadione is contraindicated in: Hypersensitivity to phytomenadione or product components; IV bolus administration without dilution is forbidden (risk of fatal anaphylactoid reactions, especially in children). Full list in the Safety section.

the vitamin K shot at birth is unnecessary, you can refuse or use drops

intramuscular K1 1 mg in the first hours of life is the unanimous recommendation of AAP, NICE, WHO, and Russian normal-pregnancy guidelines. Without prophylaxis, the late VKDB risk with intracranial haemorrhage is 4–7 per 100,000 live births. Oral regimens are acceptable when injection is refused but are less effective.

Vikasol can be given to an infant instead of K1

Vikasol is K3 (menadione sodium bisulfite), a synthetic molecule. In newborns, K3 causes haemolytic anaemia and kernicterus risk. AAP, ESPGHAN, and NICE explicitly state that only K1 (phytomenadione) is used for VKDB. International paediatric practice has not used K3 for decades. Russian package inserts still list Vikasol as a «vitamin K» drug – this is outdated practice.

vitamin K at birth is linked to childhood leukaemia

this hypothesis came from a single Golding et al. 1992 paper. Subsequent large epidemiological studies (Roman 2002, Fear 2003, McKinney 2003) did not confirm the association. AAP in its position statement explicitly rejects the hypothesis. Refusing K1 prophylaxis based on this myth raises real VKDB risk.

K1 and K2 are interchangeable – they are just vitamins K

different molecules, different target tissues, different indications. K1 (phytomenadione) acts on hepatic clotting factors – the only form for VKDB and warfarin reversal. K2 (menaquinone) acts on tissue Gla proteins – marketed for bones and vessels with weak clinical basis. They do not substitute for each other across indications.

extra K1 in adults improves clotting

in a healthy adult, vitamin K is not deficient and clotting factors synthesise normally. Supplemental K1 without a clinical indication has no effect. In patients on warfarin, supplemental K1 is dangerous – it disrupts anticoagulation.

Official sources

Direct links to regulator labels. Open in a new tab.

Other drugs in this group

Eltrombopag, Menaquinone (vitamin K2), Menaquinone-7, Tranexamic acid